Abstract
A rise in blood pressure may be produced in dogs either by partial obstruction of the renal arteries 1 or by ligation of the ureters. 2 Since the latter procedure often causes a marked decline in the renal blood flow, 3 it seems likely that the hypertension is in both instances related in some way to ischemia of the kidneys. It was shown by Tigerstedt and Bergman 4 that saline extracts of the kidney of rabbits produced a sustained rise in blood pressure when injected into other rabbits. The object of our experiments was to determine whether extracts prepared from ischemic kidneys, removed from dogs with hypertension, had a greater pressor effect than similar extracts of normal kidneys.
The freshly removed kidneys were chopped up with scissors and ground with carborundum and 0.9% salt solution. The suspension so obtained was centrifuged and the supernatant fluid was kept in the ice box until used. Amounts corresponding to 5 gm. of kidney tissue were administered intravenously to normal unanesthetized dogs. Changes in blood pressure were measured by the cuff described by Ferris and Hynes, 5 the passage of the pulse wave being determined by palpation of the dorsal artery of the foot. 6
The results which have been obtained are summarized in Table I. Extracts of the normal kidneys frequently caused a marked preliminary decline in blood pressure, followed in a few minutes by a gradual rise which persisted for 30 minutes or longer. The degree of rise varied from zero to 60 mm. of mercury above the control values. Extracts of the kidneys of dogs with renal hypertension usually caused less preliminary decline and a more marked secondary rise in blood pressure.
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